The use of precipitin analysis in agar for the study of human streptococcal infections. IV. Further observations on the purification of group A extracellular antigens.

Studies on the purification of group A streptococcal extracellular antigens detectable with naturally occurring human antibodies from normal individuals have been extended. It has been shown that streptococcal electrophoretic fractions intermediate between the most rapidly migrating components are quite complex. In the calcium phosphate chromatography of adjacent electrophoretic fractions, particular antigenic components desorbed at similar buffer elution steps. It is clear from the results obtained that substantially more extracellular antigens than the twelve heretofore recognized are secreted in human beings during infection, as judged by their detection with human antibodies. The precise number is not yet known, but is probably greater than 16. Of the nine components which thus far have been separated rather well from the others, four were previously identified as streptolysin "O," diphosphopyridine nucleotidase, proteinase precursor, and desoxyribonuclease B. The accumulated data substantiated these previous identifications. The identity of a fifth antigen has been made as a possible complex of C carbohydrate and protein. Tentative evidence for the relationship of a sixth component to scarlet fever toxin has been presented. It has been shown that rechromatography of crystalline proteinase precursor and desoxyribonuclease B on calcium phosphate columns resulted in elution principally at the expected stepwise increase in buffer concentration. Attempts to isolate antigens present as mixtures in some calcium phosphate chromatographic peaks, by rechromatography on DEAE or CM cellulose columns resulted in only limited further purifications.